Human breast milk is a valuable therapy in the treatment of preterm, critically ill and other immune compromised neonates and children. Yet, for these critically ill patients, processed human donor milk poses a measure of risk, notably, from B. cereus, a ubiquitous food toxin found in about 4% of human milk samples. B. cereus is most troubling because of its ability to form a spore that cannot be killed thru standard pasteurization. Other bacteria of concern include Clostridium perfringens, Cryptosporidium parvum, Cyclospora cayatenesis, Escherichia coli, listeria monocytogenes, Salmonella, and Staphylococcus aureus. 
To further complicate things, some donors give several “clean” LOTS (free of B. cereus and other pathogens) and then a lot will be contaminated. When the milk of qualified donors is pooled, milk infected with B. cereus or other pathogens ends up contaminating other clean lots, resulting in the destruction of the entire pool. There are limits for the number of colony forming units of these bacteria and although those limits are seldom reached, any pool that exceeds those limits is discarded and cannot be used for processing. Although testing the raw milk prior to pooling is helpful, the concentration of proteins done to make certain products effectively concentrates everything in the milk, including these pathogens. While other pathogens can be eliminated with pasteurization, B. cereus pathogen cannot be eliminated with pasteurization, therefore, it is vital that the pooled product be certified free of B. cereus prior to pasteurization and filling. Further, it is desirable to provide pools of raw milk that are substantially free of pathogens prior to pasteurization, to optimize the quality and safety of the product.